sachse



H. P. SACHSE July 12,1932. RHEOSTAT Re. 18,521

Original Filed March l, 1929 2 Sheets-Sheet l @l v 112 H. P. SACHSE RHEOSTAT Re. 18,52 l

2 Sheets-Sheet 2 July 12, 1932.

vOriginal Filed March 1, 1929 Reissued July 12, 1932 UNITED STATES .lf'A'ri-:Nr OFFICE HERMAN PAUL sACIIsn, or CHICAGO, ILLINOIS, AssIGNoR To CENTRAL SCIENTIFIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS RIIEos'rAT original No. 1,839,343, dated January 5, 1932, serial No. $43,734, med Maren 1, 192e'.

reissue filed February 1, 1932. SerialNo. 590,278.

This invention relates to rheostats, and has for its principal object to provide an improved structure whereby extensive adjustments of the resistance can be made either quickly or slowly and with great accuracy.

Further objects and advantages of the in vention will become apparent as the disclosure proceeds and the description is read in connection with the accompanying drawings showing two selected embodiments, and in which Fig.- 1 is a side elevation of the familiar type of wire wound rheostat, with the invent1on applied thereto;

Fig. 2 is a transverse section taken on the line 2-2 of Fig. 1;

Fig. 3 is an enlarged section of a fragment taken on the line 3-3 of Fig. 2;

Fig. 4 is a transverse section taken on the line 4 -4 of Fig. 3 but on a reduced scale;

Fig. 5 is a horizontal section taken on the gne 5-5 of Fig. 3 but to the same scale as Fig. 6 is an enlarged side elevation of parts of a wire wound rheostat but including another embodiment of the invention;

Fig. 7 is a transverse sectional view taken on the line 7-7 of Fig. 6;

Fig. 8 is a longitudinal vertical section taken' on the line 88 of Fig. 7

Figs. 9 and 10 are a vertical transverse section and a horizontal longitudinal section, re- Spectively, taken on the lines 9 9 and 10-10 ofv Fig. 8.

But these specific illustrations and the correspondingly specific description are used solely for the purpose of disclosure, and are not intended to indicate that the invention is so limited.

The rheostat shown in Fig. 1 includes end frames 10, made of bar stock, and clamped to the ends o a tube 11 of insulating material and a bar 12 by means of bolts 13. The re'- sistance wire 14 is Wound in a helix on'tube 11, with its end turns in Contact with straps 15 to which the ends 16 of the wire 14 are madefast by the bolts 17. The straps 15 are provided with binding posts 18, and one end of the bar 121s provided with a binding post 19; Rheostats of this general construction,

Al'iphcation vfor and having a sliding contact mounted on the vbar 12, are familiar andtherefore -need not be enlarged upon. v

According to the embodimentsof the in vention here illustrated the bar A12 is triangular in cross-section (Figs. 2 and k4) and its lower edge is provided with teeth 20 composed o short segments of threads; and for the rack and cooperating Awith its sides to guide the carriage along the rack.

" A frame 28, including a base portion 29,

has downwardly directed arms 30 lying be` tween andvr guided by the respective pairs of guide flanges 24. The arms 30 are perforated in alignment to receive the trunnions 31 ofr a nut 32, having an internal thread V33 adapted to engage andcooperate with the teeth 20 ofthe rack. A leaf spring 35 rests on the upper ends of the arms 23 and has its intermediate portion in contact with the intermediate portion of the base 29 of the frame 28, and'fserves to constantlyurge the frame upwardly, and, therefore, the threads of the nut intoengagement' with the teeth of the rack.' y

The spring 35 has an extension 36` running downwardly alongone arm 23 and thence inwardly at;37 to bear on the top surface of the rack 12 and act as a stabilizer and brake. A screw 38, passing through the extension 36 and intothe arm 23, holds the springv in position.

For convenience the frame 28 is v made in two parts separated at 39, and held together by screws Y4() [which secure the frame to a hand-piece 41 of insulating material, pro- -vided with a depending flange 42.

When it is desired to make a. substantial hand-piece 41 is pressed down, compressing' directed arms pairs of flanges 44 betweenV movementof the contact 26 quickly, the

the spring 35, lowering the frame 28 and removing the threads of the nut out of engagement with the teeth of the rack. Then a light pressure in the appropriate direction will move the carriage and the contact to approximately the position desired. Upon which the arms 45 of the frame 46 are rece'ived, as in thel form Y,shown on Fig. l; but intliis instance the base 47 of the frame is at the bottom instead ofthe top and comprises a perforated bar secured tothe arms by screws 48. i,

The nut 49 has trunnion bearings in the arms 45 and cooperates with the rack in much the same way as in the form shown on sheet 1. The hand-piece 50 has a flange 51, the end portions ofwhich are secured to the upper ends of the arms of the carriage43 by screws 52. Aleaf spring 53, having its intermediate bowed portion made fast to the hand-piece at 54, has itsends in slots 55in the arms 45 of the frame 46.

As in the other Ymodification the spring urges the frame to hold the threads of the nut 49 in engagement with the rack. This engagementof the threads with the rack, however, is obtained by turning the screw 56 which extends through the base 47 of the frame and is threaded into the base yof the carriage. Turning the screw clockwise will lower the frame against the resistance of the `spring 53 and disengage the nut from the rack. Reverse movement will permit the Aspring to effectively engage'it.

A springl brake 57, mounted on the carriage `and cooperating with the `under surface of the rack, serves to stabilize -the carriage. YWhen the nut is disengaged from the rack the carriage can be moved back andv forth as is customary with allvr/heostats of this type, but when it is desired to make accurate adjustments or continued slow adjustments, the nut mayV be permitted to engage the rack.

VI claim as my invention l. In a rheostat, a rack, a carriage engaged with the rack to travel along it, a sliding contact mounted,v to travel with the carriage, a frame associatedwith the'carriage having limited movement relative to it, a nut journaled in the frame adapted to engage the rack to give slow motion and accurate adjustment to the contact and to be disengaged from the rack to releasethe contact for rapid adjustment, and means for holding the nut engaged L- with the rack.

2. In a rheostat,a rack, a carriage engaged with the rack to travel along it, a sliding contact mounted to travel with the carriage, a frame associated with the carriage having limited movement relative to it, a nut journaled in the frame adapted to engage the rack to give slow motion and accurate adjustment to the contact and to be disengaged from the rack to release the contact for rapid adjustment, and resilient means acting between the carriage and :trame to urge the nut into yielding engagement with the rack.

3. In a rheostat, a rack, a carriage engaged with the rack to travel along it, a frame telescopically mounted with respect to the carriage,v a nut journaled in the Aframe and adapted to engage the teeth of the rack, and yielding means partially urging the nut to engage the rack.

4. In a rheostat, a sliding contact, a carriage for the Contact, a rack alongwhichy the carriage moves to shift the contact, a nut adapted to engage the rack to give slow mo tion and accurate adjustment to the'contact and to be disengaged from the rack to release the contact for rapid adjustment, a frame loosely associated with Vthe carriagerand in which the nut is rotatably journaled, and yielkding means urging the nut to engage the rac 5. In a rheostat of the type including a resistance element and a slider movable along the element, the combination of a rack bar parallel to the resistance element, an internally threaded nut sleeved on the bar adapted Vto propel the slider along the bar when the nut is rotated, and means for quickly releas- 6. In a rheostat of the type including a resistance element and a slider movable along the element, the combination of a triangular rack bar parallel to the element and having rack teeth on one apex, an internally threaded nut sleeved upon the bar and engageable with the rack teeth, and spring means holding the nut inlengagement with the rack teeth but adapted to be quickly released forvmaking rapid adjustments.

7. In a rheostat, a rack, a carriage mounted solely on the rack and engaged therewith to ,travel along it, a rotatable element mounted in the carriage and engaged `with the rack, and spring Ameans mounted inthe carriage and .urging the rotatable element into engagement vwith the rack.-

10CA y IIL.'

mounted solely on the rod and provided with a slide contacting with the resistance element,

a hand piece provided on the carriage whereby the carriage may be bodily moved for 5 rough adjustments, a rotatable element jour- -nalled in the carriage, engaged with the notches on the rod, and operable from the carriage for making fine adjustments, and

spring means mounted in the carriage and bearing against the opposite side of the rod for urging the rotatable means into meshinvr engagement with the notched side of the roda.

9. In a rheostat, a pair of end standards,

a resistance element mounted therebetween,

a conductive rack liXed against rotation in said standards and electrically connected to a terminal, a carriage having opposite end walls apertured to receive the rack carrying a brush electrically connected with the rack and in wiping engagement with the resistance element1 and an element rotatably mounted in the carriage between said end walls and meshed with the rack, said carriage being mounted solely on and freely movable back "5 and forth along the rack by rotation of the element and adapted to rest in any of a plurality of adjusted positions thereon.

In testimony whereof I aiiix my signature.

so HERMAN PAUL SACHSE. 

